MULTIPLE REFLECTIONS OF SEISMIC ENERGY

Geophysics ◽  
1948 ◽  
Vol 13 (1) ◽  
pp. 58-85 ◽  
Author(s):  
Raul F. Hansen ◽  
Curtis H. Johnson
Keyword(s):  
Cross Sections ◽  
Average Velocity ◽  
Quantitative Methods ◽  
Seismic Energy ◽  
Graphical Form ◽  
Multiple Reflections ◽  
The Earth ◽  
Straight Line ◽  
Considerable Work

This paper is a report of observations of multiple reflections in seismograph work in Argentina, of successful methods of identifying them, and of unsuccessful attempts to eliminate them. The paper begins with generalizations regarding the expectancy of multiples and develops geometrically (using straight‐line paths) the relation between multiples and their primary reflections for the cases of multiple reflection between a horizon and the surface and between two horizons, as regards time of reflection, dip and average velocity. The importance of a sharp reflecting contrast at the surface is emphasized, and it is concluded that the base of weathering may be more important in the formation of multiples than the surface of the earth. Early observations of multiple reflections from a volcanic flow and from a shallow basement are described. Other areas showed discordant data on the seismograms and cross sections, which, if due to multiples, could only be caused by multiple reflections from good sedimentary reflectors. In these areas a method for identifying both types of multiple reflections by their low average velocity as obtained by shooting reflection velocity‐profiles was developed, the work being facilitated by considerable knowledge of velocity and section from previous refraction shooting. Though this reflection velocity‐profile method is considered essential to positive and detailed identification of multiples, two methods of multiple identification using ΔT variations in continuous profiling are described and the results of considerable work with one of them are reported in graphical form, showing not only a separation of multiple from real reflections but also the determination of the true velocity‐depth function by means of the real reflections so segregated. Experiments are briefly described in which variations in size or depth of shot and variations in filters were not effective in reducing the ratio of multiple reflections to real reflections. The paper closes with suggestions for identifying multiple reflections by their abnormal curvatures in discontinuous, symmetrical‐spread dip shooting, and for using primitive qualitative methods where the topography or subsurface are not suited to the quantitative methods developed here.

THE USE OF CUMULATIVE RESISTANCE IN EARTH-RESISTIVITY SURVEYS

1945 ◽  
Vol 23a (4) ◽  
pp. 57-72 ◽  
Author(s):  
R. Ruedy
Keyword(s):  
Apparent Resistivity ◽  
Middle Layer ◽  
The Other ◽  
Electrode Spacing ◽  
Line Graphs ◽  
Earth Resistivity ◽  
The Earth ◽  
Straight Line ◽  
The Individual

When the soil is assumed to consist of two layers—the upper of resistivity ρ1 and the lower of resistivity ρ2—and cumulative resistances are calculated by adding or integrating the earth-resistivity functions for intervals that are a fraction of the thickness of the upper layer, a practically linear relation is obtained between the cumulative resistance and the electrode spacing until the distance between the electrodes is equal to the thickness of the upper material. Should one of the materials be at least twice as conducting as the other, the extent of the deviation from the linear law enables the determination of the depth of the upper stratum and of the ratio between the resistivities of the two layers. When three layers are present and the middle layer is at least twice as thick as the top stratum, the thicknesses may be deduced from the two departures of the cumulative resistances from the linear law. Since these conclusions are based on the theory of the individual apparent resistivity of stratified ground at various electrode spacings, they have the same range of application as the earth-resistivity curves, but the occurrence of straight line graphs facilitates the plotting and the interpretation of results based on a necessarily limited number of measurements.

Interpretation of velocity spectra

Geophysics ◽  
1980 ◽  
Vol 45 (12) ◽  
pp. 1741-1752 ◽  
Author(s):  
Allen B. Cunningham ◽  
Harland H. Heffring
Keyword(s):  
Linear Time ◽  
Data Gathering ◽  
Multiple Reflections ◽  
Machine Method ◽  
Straight Line ◽  
Composite Section ◽  
Seismic Sections ◽  
Velocity Spectra ◽  
The Individual

One major effort in processing seismic data is that of correcting for the geometric effects or normal moveout introduced by multichannel data gathering procedures. Usually, this involves detecting coherent reflected signals, determining a time (t) versus moveout (Δt) relationship for these signals, time correcting the individual receiver traces, and combining selected traces into a stacked or composite section. Most of these operations are automated. Several velocity analysis techniques are available for detecting reflections automatically, and individual trace correcting and combining procedures are trivial. However, determination of a moveout function which will discriminate among valid reflections, multiple reflections, and noise is still largely a human operation. We describe a machine method devised to determine automatically these moveout, or t‐Δt, functions, as they are commonly called. The method makes extensive use of the observed phenomenon that the t‐Δt function is well approximated by a segmented straight‐line curve when plotted on a logarithmic moveout (Δt) versus linear time (t) graph. Criteria for determining these straight‐line functions, which include a constraint on the line segment slopes, are discussed; several examples resulting from their use are shown. In the examples, seismic sections corrected by our machine‐derived moveout functions are compared with those corrected by more conventionally determined functions.

scholarly journals DETERMINATION OF AN OPTIMAL PROCESSING FLOW FOR THE SUPPRESSION OF FREE-SURFACE MULTIPLES IN REAL 2D MARINE DATA

2013 ◽  
Vol 31 (1) ◽  
pp. 137
Author(s):  
Andrei Gomes de Oliveira ◽  
Ellen De Nazaré Souza Gomes
Keyword(s):  
Cross Sections ◽  
Multiple Reflections ◽  
Optimal Processing ◽  
Predictive Deconvolution ◽  
Air Water Interface ◽  
P Domain ◽  
Marine Data ◽  
Multiple Elimination ◽  
Processing Flow

The presence of multiple reflections is common in marine surveys due to the air-water interface. Multiples have significant energy and can mask deep reflectors, leading to the misinterpretation of seismic cross-sections. In this study, surface-related multiple elimination (SRME), predictive deconvolution in the domain τ − p domain and Radon and f − k filtering are used to eliminate surface multiples in real 2D marine data. These methods are applied in different combinations, and the results are analyzed with the aim of determining an optimal seismic processing flow for the removal of surface multiples. RESUMO: No levantamento marinho é comum a presença de reflexões múltiplas devido à interface ar-água. Essas reflexões múltiplas possuem energia considerável e podem mascarar reflexões primárias levando a erros de interpretação da seção sísmica. Neste trabalho é determinado um fluxo ótimo de processamento sísmico para atenuação de múltiplas de superfície. Os métodos de eliminação de múltiplas de superfície (SRME), deconvolução preditiva no domínio τ − p e as filtragens Radone f − k são aplicados a um dado marinho real 2D em diferentes combinações. Os resultados são analisados com objetivo de determinar um fluxo de processamento sísmico ótimo para atenuação de múltiplas de superfície.Palavras-chave: atenuação de múltiplas de superfície; SRME; filtragem Radon; deconvolução preditiva no domínio τ − p; filtragem f − k

scholarly journals Haversine Method in Looking for the Nearest Masjid

2017 ◽  
Author(s):  
Andysah Putera Utama Siahaan
Keyword(s):  
Euclidean Distance ◽  
Google Maps ◽  
The Earth ◽  
Straight Line ◽  
Excellent Method

Determination of the nearest distance is often a problem to get to somewhere. This happens when Muslims want to find masjid when they want to worship. As the time of worship is nearing its end, they are very confused to find the nearest masjid from their location. In manual calculations, this is very difficult to do where several masjids become an option. The Haversine method is an excellent method for finding the nearest place based on the coordinates of the earth. This method will calculate the distance with the Euclidean distance algorithm based on the latitude and longitude of the earth. These values are obtained by using Google Maps. On Google Maps, certain points have specific longitude and latitude. It is very helpful in determining the points of the masjid's location. This study performs these calculations to get the closest distance from the search. It is done based on a straight line between the user's position and the target. The weakness of this algorithm, it can not know the obstacles that exist into the nearest masjid. This algorithm only calculates the distance based on a straight line. However, it is helpful for people to find the nearest masjid from their position.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

Gender determination of caucasoid hair using image analysis

1993 ◽  
Vol 51 ◽  
pp. 216-217
Author(s):  
T.B. Ball ◽  
W.M. Hess
Keyword(s):  
Image Analysis ◽  
Cross Sections ◽  
Scalp Hair ◽  
The Body ◽  
Equivalent Diameter ◽  
Cross Sectional ◽  
Hair Samples ◽  
Length Width ◽  
Morphological Differences

It has been demonstrated that cross sections of bundles of hair can be effectively studied using image analysis. These studies can help to elucidate morphological differences of hair from one region of the body to another. The purpose of the present investigation was to use image analysis to determine whether morphological differences could be demonstrated between male and female human Caucasian terminal scalp hair.Hair samples were taken from the back of the head from 18 caucasoid males and 13 caucasoid females (Figs. 1-2). Bundles of 50 hairs were processed for cross-sectional examination and then analyzed using Prism Image Analysis software on a Macintosh llci computer. Twenty morphological parameters of size and shape were evaluated for each hair cross-section. The size parameters evaluated were area, convex area, perimeter, convex perimeter, length, breadth, fiber length, width, equivalent diameter, and inscribed radius. The shape parameters considered were formfactor, roundness, convexity, solidity, compactness, aspect ratio, elongation, curl, and fractal dimension.

HADIS KURAIB DALAM KONSEP RUKYATUL HILAL

1970 ◽  
Vol 13 (2) ◽  
Author(s):  
Muslih Husein
Keyword(s):  
The West ◽  
The Earth ◽  
New Moon ◽  
The Republic

Hisab dan rukyat, hakikatnya, adalah cara untuk mengetahui pergantian bulan. Kajian ini memperlihatkan beberapa temuan. Pertama, korelasi antara hadis Kuraib dan terjadinya perbedaan penetapan awal Ramadan, Syawal, dan Dzul Hijjah di Indonesia. Kementerian Agama Republik Indonesia telah menetapkan bahwa Indonesia secara keseluruhan menjadi satu wilayah hukum (wilayatul hukmi). Kedua, tentang keberhasilan rukyat al-hilal di satu kawasan yang diberlakukan bagi kawasan lain di muka bumi. Perlu diketahui bersama bahwa visibilitas pertama hilal tidak meliputi seluruh muka bumi pada hari yang sama, melainkan membelahnya menjadi dua bagian: (1) bagian sebelah Barat yang dapat melihat hilal dan (2) bagian sebelah Timur yang tidak dapat melihat hilal.Hisab and rukyat is a way to know the turn of the month. This study shows several findings. First is the correlation between Kuraib traditions and differences in the determination of the beginning of Ramadan, Shawwal, and Dhul-Hijjah in Indonesia. Ministry of Religious Affairs of the Republic of Indonesia has stated that Indonesia as a whole into a single jurisdiction (wilayatul hukmi). Second, on the success rukyat alhilal in one area that applied to other regions of earth. Important to know that the first visibility of the new moon does not cover the entire face of the earth on the same day, but splitting it into two parts: (1) part of the West to see the new moon, and (2) part of the East were not able to see the new moon.

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